Power storage module and fixing structure of power storage module

ABSTRACT

A power storage module is formed by superimposing a pair of end plates at opposite ends in the stacking direction of a plurality of power storage cells that are stacked in the stacking direction. The pair of end plates are connected by a frame holding an insulator between itself and the power storage cells. Condensed water occurring on the surface of the power storage cells could contact the end plate. There is thus a possibility that a liquid junction will be formed; when the power storage module is in a mounted state the insulator includes a first rib extending in a direction, condensed water attached to the insulator cannot flow toward the end plate due to it being blocked by the first rib, thus preventing the power storage cell from forming a liquid junction with the end plate via the condensed water.

TECHNICAL FIELD

The present invention relates to a power storage module that includes a plurality of power storage cells that are stacked in a stacking direction, a pair of end plates that are superimposed at opposite ends in the stacking direction of the power storage cells, a frame that is connected to the pair of end plates via fastening portions at opposite ends, and an insulating insulator that is held between the frame and the power storage cell, and to a fixing structure of this power storage module.

BACKGROUND ART

An arrangement in which when assembling a power storage module by connecting a pair of end plates superimposed at opposite ends in the stacking direction of a plurality of stacked power storage cells by means of a restraining band (frame) made of metal, the formation of a liquid junction between the power storage cells and a vehicle body via the frame is prevented by disposing a tray, made of an insulating body, between the power storage cells and the frame is known from Patent Document 1 below.

RELATED ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent Application Laid-open No. 2012-014962

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, in the above arrangement there is a possibility that condensed water occurring on the power storage cells will build up on the tray, the lower ends of the power storage cells will be immersed in the condensed water to thus form a liquid junction between the power storage cells, and a case of the power storage cells will corrode.

The present invention has been accomplished in light of the above circumstances, and it is an object thereof to prevent a liquid junction from being formed by condensed water occurring on a power storage cell.

Means for Solving the Problems

In order to attain the above object, according to a first aspect of the present invention, there is provided a power storage module comprising a plurality of power storage cells that are stacked in a stacking direction, a pair of end plates that are superimposed at opposite ends in the stacking direction of the power storage cells, a frame that is connected to the pair of end plates via fastening portions at opposite ends, and an insulating insulator that is held between the frame and the power storage cell, wherein n a mounted state the insulator comprises a first rib that extends in a direction intersecting the stacking direction.

Further, according to a second aspect of the present invention, in addition to the first aspect, the insulator comprises a plurality of the first ribs that extend vertically, and comprises a plurality of second ribs that connect adjacent first ribs in a V-shape.

Furthermore, according to a third aspect of the present invention, in addition to the first or second aspect, the insulator comprises a downwardly extending portion that extends further downwardly than a lower end of the frame in a vertical direction.

Moreover, according to a fourth aspect of the present invention, in addition to the third aspect, a lower edge of the downwardly extending portion bends in a zig-zag shape.

Further, according to a fifth aspect of the present invention, in addition to the third or fourth aspect, the module comprises an insulating power storage cell holder held between the end plate and the power storage cell positioned in an end part in the stacking direction, the power storage cell holder comprises a downwardly extending portion that extends further downwardly than the lower end of the frame in the vertical direction, and the downwardly extending portion of the insulator and the downwardly extending portion of the power storage cell holder surround a periphery of the plurality of power storage cells in cooperation.

Furthermore, according to a sixth aspect of the present invention, in addition to any one of the first to fifth aspects, the insulator is subjected to a water-repellent treatment.

Moreover, according to a seventh aspect of the present invention, in addition to the sixth aspect, a section, where the rib is present, of the insulator is subjected to a water-repellent treatment.

Further, according to an eighth aspect of the present invention, there is provided a fixing structure of a power storage module, the structure fixing the power storage module according to any one of the first to seventh aspects onto a support plate, wherein the support plate and the frame oppose each other, and a vertically lower end of the insulator is at a position lower than the support plate in the vertical direction.

End power storage cell holders 12A and 12B of an embodiment correspond to the power storage cell holder of the present invention, a first wall portion 12 g, a fifth wall portion 18 e, and a third wall portion 19 c of the embodiment correspond to the downwardly extending portion of the present invention, an upper frame 15 and a lower frame 16 of the embodiment correspond to the frame of the present invention, and an upper insulator 18 and a lower insulator 19 of the embodiment correspond to the insulator of the present invention.

Effects of the Invention

In accordance with the first aspect of the present invention, the power storage module is formed by superimposing the pair of end plates at opposite ends in the stacking direction of the plurality of power storage cells that are stacked in the stacking direction, and connecting the pair of end plates by means of the frame holding the insulating insulator between itself and the power storage cells. If condensed water occurring on the surface of the power storage cells flows along the insulator and contacts the end plate, there is a possibility that a liquid junction will be formed; since when the power storage module is in a mounted state the insulator includes the first rib extending in a direction intersecting the stacking direction, condensed water attached to the insulator cannot flow toward the end plate due to it being blocked by the first rib, thus preventing the power storage cell from forming a liquid junction with the end plate via the condensed water. Furthermore, since condensed water flows downwardly from the insulator and is discharged, it is also possible to prevent the formation of a liquid junction between the power storage cells.

Furthermore, in accordance with the second aspect of the present invention, since the insulator includes the plurality of vertically extending first ribs and also includes the plurality of second ribs connecting adjacent first ribs in a V shape, condensed water temporarily builds up between the first and second ribs, and after a fixed amount of condensed water has built up it is made to drop dowry thus making it difficult for uninterrupted condensed water to occur, it is possible to prevent an electrical connection between the power storage cell and a component, made of metal, in the vicinity thereof via uninterrupted condensed water, and as a result the formation of a liquid junction can be prevented.

Moreover, in accordance with the third aspect of the present invention, since the insulator includes the downwardly extending portion that extends further downwardly than the lower end of the frame in the vertical direction, it makes it difficult for condensed water flowing downwardly along the insulator to contact the frame, thus preventing a liquid junction from forming between the power storage cell and the frame and thereby preventing current from passing to the end plate.

Furthermore, in accordance with the fourth aspect of the present invention, since the lower edge of the downwardly extending portion of the insulator bends in a zig-zag shape, it is possible to improve the drainage of condensed water from the downwardly extending portion, thus preventing effectively a liquid junction from forming between the power storage cell and the frame.

Moreover, in accordance with the fifth aspect of the present invention, there is further provided the insulating power storage cell holder held between the end plate and the power storage cell positioned in an end part in the stacking direction, the end holder includes the downwardly extending portion extending further downwardly than the lower end of the frame in the vertical direction, the downwardly extending portion of the insulator and the downwardly extending portion of the power storage cell holder surround the periphery of the plurality of power storage cells in cooperation, and it is therefore possible to enclose condensed water occurring on the plurality of power storage cells by means of the two downwardly extending portions, thus making it difficult for it to contact the frame or the end plate outside it.

Furthermore, in accordance with the sixth aspect of the present invention, since the insulator is subjected to a water-repellent treatment, it is possible to prevent condensed water from becoming attached to the insulator, thus promoting drainage.

Moreover, in accordance with the seventh aspect of the present invention, since the section, where the rib is present, of the insulator is subjected to a water-repellent treatment, it is possible to promote drainage with the minimum water-repellent treatment.

Furthermore, in accordance with the eighth aspect of the present invention, the support plate and the frame oppose each other, the vertically lower end of the insulator is at a position that is lower than the support plate in the vertical direction, and it is therefore possible to prevent condensed water that has flowed down along the insulator from contacting the support plate, thus preventing a liquid junction from being formed via the support plate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a power storage module. (first embodiment)

FIG. 2 is an exploded perspective view of the power storage module. (first embodiment)

FIG. 3 is a perspective view of a power storage pack. (first embodiment)

FIG. 4 is a view in the direction of arrow 4 in FIG. 1. (first embodiment)

FIG. 5 is a view in the direction of arrow 5 in FIG. 1. (first embodiment)

FIG. 6 is a view in the direction of arrow 6 in FIG. 4. (first embodiment)

FIG. 7 is a sectional view along line 7-7 in FIG. 6. (first embodiment)

FIG. 8 is a view from arrowed line 8-8 in FIG. 4. (first embodiment)

FIG. 9 is a sectional view along line 9-9 in FIG. 8. (first embodiment)

FIG. 10 is a view in the direction of arrow 10 in FIG. 5. (first embodiment)

FIG. 11 is a view in the direction of arrow 11 in FIG. 5. (first embodiment)

FIG. 12 is a table showing types of water-repellent treatment for an insulator. (first embodiment)

FIG. 13 is a diagram showing the state of a water droplet attached to the insulator. (first embodiment)

EXPLANATION OF REFERENCE NUMERALS AND SYMBOLS

-   11 Power storage cell -   12A End power storage cell holder (power storage cell holder) -   12B End power storage cell holder (power storage cell holder) -   12 g First wall portion (downwardly extending portion) -   14 End plate -   15 Upper frame (frame) -   15 a Fastening portion -   16 Lower frame (frame) -   16 a Fastening portion -   18 Upper insulator (insulator) -   18 e Fifth wall portion (downwardly extending portion) -   18 f First rib -   18 g Second rib -   19 Lower insulator (insulator) -   19 c Third wall portion (downwardly extending portion) -   29 Support plate -   M Power storage module

MODE FOR CARRYING OUT THE INVENTION

A mode for carrying out the present invention is explained below by reference to FIG. 1 to FIG. 13.

First Embodiment

As shown in FIG. 1 and FIG. 2, a power storage module M, which is used as a power supply device for an electric automobile or a hybrid automobile, includes a predetermined number (12 in the embodiment) of power storage cells 11 that are stacked in a stacking direction. Each power storage cell 11 formed from for example a lithium ion battery is formed into a rectangular parallelepiped and includes a pair of mutually opposing main faces 11 a and 11 a, a pair of mutually opposing side faces 11 b and 11 b perpendicular to the main faces 11 a and 11 a, and mutually opposing top face 11 c and bottom face 11 d perpendicular to the main faces 11 a and 11 a and the side faces 11 b and 11 b, positive and negative electrodes 11 e and 11 e being provided on the top face 11 c.

The pair of main faces 11 a and 11 a and the pair of side faces 11 b and 11 b of each power storage cell 11 are covered by a condensation-preventing sheet made of a synthetic resin, thus making it difficult for condensed water to be formed on the surface of the power storage cell 11, which is made of metal. However, the top faces 11 c and the bottom face 11 d of each power storage cell 11 are not covered by a condensation-preventing sheet, and the metal surface is exposed.

In the present specification, a direction that is perpendicular to the stacking direction and joins the top face 11 c and the bottom face 11 d of the power storage cell 11 is defined as the up-and-down direction, and a direction that is perpendicular to the stacking direction and joins the pair of side faces 11 b and 11 b of the power storage cell 11 is defined as the left-and-right direction.

The main faces 11 a of twelve of the power storage cells 11 and eleven rectangular plate-shaped intermediate power storage cell holders 12, made of a synthetic resin, are superimposed in turn in the stacking direction, a pair of rectangular plate-shaped end power storage cell holders 12A and 12B, made of a synthetic resin, are superimposed on outer sides, in the stacking direction, of the two power storage cells 11 and 11 at opposite ends in the stacking direction, and a pair of end plates 14 and 14, made of metal, are further superimposed on outer sides thereof in the stacking direction. The eleven intermediate power storage cell holders 12 are members having an interchangeable identical shape, and the pair of end power storage cell holders 12A and 12B are members having shapes that are different from that of the intermediate power storage cell holders 12 and having mutually different shapes.

In a state in which the power storage cells 11, the intermediate power storage cell holders 12, the end power storage cell holders 12A and 12B, and the end plates 14 and 14 are stacked in the stacking direction, four corners of the pair of end plates 14 and 14 are linked to each other by means of upper frames 15 and 15 formed from a pair of rod-shaped members made of metal and having an L-shaped cross section, and lower frames 16 and 16 formed from a pair of rod-shaped members made of metal and having an L-shaped cross section, thus carrying out assembly of the power storage module M. That is, the power storage module M is assembled by abutting thick fastening portions 15 a provided at opposite ends of the upper frames 15 and 15 and thick fastening portions 16 a provided at opposite ends of the lower frames 16 and 16 against the four corners of the end plates 14 and 14, and screwing bolts 17 extending through the end plates 14 and 14 into the fastening portions 15 a, 16 a.

In this arrangement, in order to prevent condensed water from forming a liquid junction between the power storage cells 11 and the upper frames 15 and 15, upper insulators 18 and 18, made of a synthetic resin, are disposed between the upper frames 15 and 15 and the power storage cells 11, intermediate power storage cell holders 12, and end power storage cell holders 12A and 12B. Similarly, in order to prevent condensed water from forming a liquid junction between the power storage cells 11 and the lower frames 16, lower insulators 19 and 19, made of a synthetic resin, are disposed between the lower frames 16 and 16 and the power storage cells 11, intermediate power storage cell holders 12, and end power storage cell holders 12A and 12B. Furthermore, plate springs 20 and 20 for preventing the occurrence of rattling by pushing the bottom faces 11 d of the power storage cells 11 upward are disposed between the lower frames 16 and 16 and the lower insulators 19 and 19.

Each of the intermediate power storage cell holders 12 and the end power storage cell holders 12A and 12B includes a plate-shaped plate portion 12 a, four engagement portions 12 b projecting in the stacking direction from four corners of the plate portion 12 a, a thermistor retaining portion 12 c provided in a middle part at the lower end of the plate portion 12 a, and a plate-shaped shielding portion 12 d projecting in the stacking direction from a middle part in the left-and-right direction of the upper edge of the plate portion 12 a. However, the end power storage cell holder 12A alone on one end side in the stacking direction does not include the thermistor retaining portion 12 c, and the end power storage cell holder 12B alone on the other end side in the stacking direction does not include the shielding portion 12 d.

As shown in FIG. 2, FIG. 10, and FIG. 11, the thermistor retaining portions 12 c of the intermediate power storage cell holders 12 and the other end power storage cell holder 12B are linked to each other due to engagement between pins 12 e and pin holes 12 f, a thermistor 21A is fitted into the thermistor retaining portion 12 c of the intermediate power storage cell holder 12 positioned at one end in the stacking direction, the thermistor 21A measuring temperature by being in contact with the bottom face 11 d of the power storage cell 11 positioned at said one end in the stacking direction, and a thermistor 21B is fitted into the thermistor retaining portion 12 c of the end power storage cell holder 12B positioned at the other end in the stacking direction, the thermistor 21B measuring temperature by being in contact with the bottom face 11 d of the power storage cell 11 positioned at said other end in the stacking direction.

Harnesses 22 and 22 extending from the thermistor 21A are retained in the interior of a harness holder 24 formed into a sheath shape from a synthetic resin. The harnesses 22 and 22 of the thermistor 21A extending from the other end side in the stacking direction of the harness holder 24 are superimposed on the other thermistor 21B, a total of four harnesses 22 of the thermistors 21A and 21B being bound there and covered by a harness cover 25. A connector 26 provided at tips of the four harnesses 22 coming out from the harness cover 25 is connected to an electronic control unit 27 (see FIG. 5) provided on the other end plate 14.

As shown in FIG. 1 and FIG. 4, among the top faces 11 c of the twelve power storage cells 11, the intermediate part in the left-and-right direction is covered by the shielding portions 12 d of the intermediate power storage cell holders 12 and the end power storage cell holder 12A, and opposite end parts in the left-and-right direction, from which the electrodes 11 e project, are covered by a bus bar plate 28 formed into a U-shape from an insulating material. The bus bar plate 28 has a metal plate that electrically connects in series the electrodes 11 e of the twelve power storage cells 11.

As shown in FIG. 3, six of the power storage modules M are supported on one support plate 29, made of metal, to thus form a power storage pack P. In this arrangement, the power storage modules M are arranged in an attitude in which they are tilted through 90° so that the left-and-right direction becomes the vertical direction, and upper faces thereof on which the bus bar plates 28 are provided face opposite directions in turn. Six rectangular openings 29 a are formed in the support plate 29 so as to oppose one of left and right side faces of the six power storage modules M, and an annular seal member 30 formed from an elastic member such as a foam rubber is disposed on the periphery of each opening 29 a. In a vehicle-mounted state as shown in FIG. 3, the left-and-right direction defined for FIG. 1 and FIG. 2 becomes the vertical direction, and the up-and-down direction defined for FIG. 1 and FIG. 2 becomes the horizontal direction.

As shown in FIG. 2, FIG. 4, and FIG. 6 to FIG. 8, the upper insulator 18 is a member molded as a unit from a synthetic resin, and its constant cross section in the stacking direction includes a first wall portion 18 a, a second wall portion 18 b, a third wall portion 18 c, a fourth wall portion 18 d, and a fifth wall portion 18 e (see FIG. 7); a vertical wall 15 b, which is vertical in a vehicle-mounted state, of the upper frame 15 having an L-shaped cross section is covered by the first wall portion 18 a, the second wall portion 18 b, and the third wall portion 18 c, and an upper face of a horizontal wall 15 c, which is horizontal in the vehicle-mounted state, of the upper frame 15 is covered by the fourth wall portion 18 d. The extremity of the fifth wall portion 18 e, which extends downwardly from the fourth wall portion 18 d in the vertical direction in the vehicle-mounted state, bends in a zig-zag manner.

Furthermore, a large number of first ribs 18 f, which extend vertically in the vehicle-mounted state, are formed in parallel on an outer face, which extends substantially flush with the top faces 11 c of the power storage cells 11, of the first wall portion 18 a, and a plurality of second ribs 18 g providing a connection between two adjacent first ribs 18 f and 18 f are formed into a V-shape on the outer face. The second ribs 18 g of the upper insulator 18 positioned on the upper side in the vertical direction in the vehicle-mounted state are disposed in an inverted V-shape, but the second ribs 18 g of the upper insulator 18 positioned on the lower side in the vertical direction in the vehicle-mounted state are disposed in a V-shape (see FIG. 4).

Furthermore, a lower face of the horizontal wall 15 c of the upper frame 15 positioned on the lower side in the vertical direction in the vehicle-mounted state and the lower end, in the vertical direction, of the first wall portion 18 a of the upper insulator 18 positioned on the lower side in the vertical direction in the vehicle-mounted state oppose an upper face of the support plate 29, and the lower end, in the vertical direction, of the fifth wall portion 18 e of the upper insulator 18 positioned on the lower side in the vertical direction in the vehicle-mounted state extends downwardly beyond the edge of the opening 29 a of the support plate 29. In this arrangement, the seal member 30 is held between the lower face of the horizontal wall 15 c of the upper frame 15 and the edge of the opening 29 a of the support plate 29 (see FIG. 7). As shown in FIG. 7, the lower end of the first wall portion 18 a is positioned on the lower side in the vertical direction relative to the lower face of the horizontal wall 15 c of the upper frame 15.

As shown in FIG. 2, FIG. 5, FIG. 6, and FIG. 8, the lower insulator 19 includes a first wall portion 19 a extending along the bottom faces ltd of the power storage cells 11, a second wall portion 19 b rising from the first wall portion 19 a and extending along the side faces 11 b of the power storage cells 11, and a third wall portion 19 c rising from the second wall portion 19 b and extending in a direction away from the side faces 11 b of the power storage cells 11, the extremity of the third wall portion 19 c bending in a zig-zag manner.

The third wall portion 19 c of the lower insulator 19 and the fifth wall portion 18 e of the upper insulator 18 have an identical shape (see FIG. 6) and are positioned in parallel to each other with a predetermined gap along the stacking direction. Therefore, in the same way as for the fifth wall portion 18 e of the upper insulator 18, in the vehicle-mounted state the lower end, in the vertical direction, of the third wall portion 19 c of the lower insulator 19 extends downwardly beyond the edge of the opening 29 a of the support plate 29, and the seal member 30 is held between a lower face of the horizontal wall 16 c of the lower frame 16 (see FIG. 8) and the edge of the opening 29 a of the support plate 29.

First wall portions 12 g and 12 g project from left and right end parts of the end power storage cell holders 12A and 12B, and extremities of the first wall portions 12 g and 12 g bend in a zig-zag manner. The fifth wall portion 18 e of the upper insulator 18, the third wall portion 19 c of the lower insulator 19, and the first wall portions 12 g and 12 g of the end power storage cell holders 12A and 12B are connected to each other to thus form a rectangular frame (see FIG. 6), and in the vehicle-mounted state the lower end, in the vertical direction, of the rectangular frame extends downwardly beyond lower ends, in the vertical direction, of the power storage cells 11 and the end plates 14 and 14 and beyond the edge of the opening 29 a of the support plate 29.

As shown in FIG. 5, FIG. 10, and FIG. 11, opposite end parts in the left-and-right direction of the bottom faces 11 d of the power storage cells 11 forming the power storage module M are completely covered by the first wall portions 19 a and 19 a of the pair of the lower insulators 19 and 19, and a section sandwiched by the pair of first wall portions 19 a and 19 a is partially covered by the thermistor retaining portions 12 c of the intermediate power storage cell holders 12 and the end power storage cell holder 12B on said other end side. A first partition wall 19 d bending in a zig-zag manner in the left-and-right direction and extending in the stacking direction is projectingly provided on a lower face of the first wall portion 19 a. In the vehicle-mounted state in which the bottom faces 11 d of the power storage cells 11 face the vertical direction (see FIG. 5), the first partition wall 19 d, which bends in a zig-zag manner, attains a shape in which a large number of V shapes are connected.

The upper insulator 18 and the lower insulator 19 are subjected to a water-repellent treatment in order to make it difficult for condensed water to become attached thereto, thereby promoting the drainage of condensed water.

As shown in FIG. 12, water-repellent treatments for the upper insulator 18 and the lower insulator 19 can be roughly divided into a fluorine treatment and a cleaning treatment. The fluorine treatment involves formation of a PTFE (polytetrafluoroethylene) film by a method such as coating, spraying, or plasma irradiation, thus making it difficult for condensed water to become attached. Furthermore, the cleaning treatment involves removing dirt from a surface by means of degreasing spray cleaning or ultrasonic cleaning, thus making it difficult for condensed water to become attached thereto.

The strength of the water-repellent treatment is represented by the contact angle of a water droplet (see FIG. 13); a contact angle of 90° or greater can be obtained by formation of a PTFE film or degreasing spray cleaning, and a contact angle of 120° or greater can be obtained by ultrasonic cleaning due to the water repellency being further enhanced.

In addition, it is not necessary to subject the whole of the upper insulator 18 and the lower insulator 19 to a water-repellent treatment, and only a section where the rib is present (e.g. the first ribs 18 f and 18 f or the second ribs 18 g of the upper insulator 18) may be subjected to a water-repellent treatment. By so doing, it is possible to promote drainage of water with the minimum water-repellent treatment.

As shown in FIG. 5, FIG. 10, and FIG. 11, second partition walls 12 j and 12 j project downwardly from lower ends of the pair of end power storage cell holders 12A and 12B. The second partition walls 12 j and 12 j of the end power storage cell holders 12A and 12B form a rectangular frame in cooperation with the first partition walls 19 d and 19 d of the pair of the lower insulators 19 and 19, and this frame surrounds the periphery of the thermistor retaining portions 12 c of the intermediate power storage cell holders 12 and the end power storage cell holder 12B on said other end side.

As shown in FIG. 8 and FIG. 9, the end power storage cell holder 12A on said one side includes a pair of first guide ribs 12 h and 12 h and a pair of second guide ribs 12 i and 12 i surrounding the plate portion 12 a. The pair of first guide ribs 12 h and 12 h extend along the pair of side faces 11 b and 11 b of the power storage cells 11, separating parts a at opposite ends thereof curving into an arc-shape curve so as to move away from the fastening portions 15 a 15 a, 16 a, 16 a of the upper frames 15 and 15 and the lower frames 16 and 16. The pair of second guide ribs 12 i and 12 i extend along the top face 11 c and the bottom face 11 d of the power storage cells 11, and opposite ends thereof are superimposed on opposite ends of the pair of first guide ribs 12 h and 1211 via a cutout Two guide parts b extend from part of each of the pair of first guide ribs 12 h and 12 h extending along the pair of side faces 11 b and 11 b of the power storage cells 11, the guide parts b extending in directions in which they approach each other.

A first drainage channel 31 is formed on a first face P1, on the end plate 14 side, of the end power storage cell holder 12A (see FIG. 9). In the vehicle-mounted state, the first drainage channel 31 extends downwardly in the vertical direction along the plate portion 12 a of the end power storage cell holder 12A, and the lower end thereof is bent through 90° in a substantially horizontal direction by means of the first guide rib 12 h. In this arrangement, the first guide rib 12 h is inclined with respect to the horizontal direction so that the extremity side is slightly lower. On the other hand, a second drainage channel 32 is formed on a second face P2, on the power storage cells 11 side, of the end power storage cell holder 12A (see FIG. 9). In the vehicle-mounted state, the second drainage channel 32 extends downwardly in the vertical direction along the plate portion 12 a of the end power storage cell holder 12A.

The edge of the opening 29 a of the support plate 29 is positioned between an outlet 31 a of the first drainage channel 31 and an outlet 32 a of the second drainage channel 32, and the edge is set so as to be at a height that is lower than the height of the outlet 31 a of the first drainage channel 31 and higher than the height of the outlet 32 a of the second drainage channel 32. Furthermore, the support plate 29 is inclined so that the first drainage channel 31 side is slightly lower than the second drainage channel 32 side. The seal member 30 is disposed between the edge of the opening 29 a of the support plate 29 and the lower face of the first guide rib 12 h. The seal member 30 is originally for preventing the leakage of cooling air for cooling the power storage cells 11, but in the present embodiment it exhibits a function of preventing the leakage of condensed water in addition to the above function.

The structure of the end power storage cell holder 12A on one side is explained above, but the structure of the end power storage cell holder 12B on the other side is substantially the same.

The operation of the embodiment of the present invention having the above arrangement is now explained.

Among the surfaces of the power storage cells 11 forming the power storage module M, the main faces 11 a and 11 a and the side faces 11 b and 11 b are covered by the condensation-preventing sheet and it is therefore relatively difficult for condensed water to form thereon, but the top face 11 e and the bottom face 11 d are not covered by the condensation-preventing sheet, and it is therefore relatively easy for condensed water to form. When galvanic water whose potential has been increased by contacting the electrodes 11 e of the power storage cells 11 forms a liquid junction with the upper frames 15 and 15 or the lower frames 16 and 16, there is a possibility that current will flow from the upper frames 15 and 15 or the lower frames 16 and 16 to the vehicle body via the end plates 14 and 14, and it is therefore necessary to suppress the formation of a liquid junction between the power storage cells 11 and the upper frames 15 and 15 and lower frames 16 and 16 or between the power storage cells 11 and the end plates 14 and 14.

Since the intermediate power storage cell holders 12, which are made of a synthetic resin, are disposed between adjacent power storage cells 11, the end power storage cell holders 12A and 12B, which are made of a synthetic resin, are disposed between the power storage cells 11 and the end plates 14 and 14, the upper insulators 18 and 1$, which are made of a synthetic resin, are disposed between the power storage cells 11 and the upper frames 15 and 15, and the lower insulators 19 and 19, which are made of a synthetic resin, are disposed between power storage cells 11 and the lower frames 16 and 16, the formation of a liquid junction can be suppressed to some extent by means of these synthetic resin members, but it is necessary to take measures assuming a case in which a large quantity of condensed water is formed.

Since the power storage module M is mounted on a vehicle in manner which it is tilted through 90° such that one of the side faces 11 b of the power storage cells 11 faces downward in the vertical direction, it is important to provide electrical shielding between, among the pair of upper frames 15 and 15 and the pair of the lower frames 16 and 16, the upper frame 15 and lower frame 16 that are on the lower side in the vehicle-mounted state and the upper insulator 18 and lower insulator 19 e on the lower side in the vertical direction, Which cover them.

Among the surfaces of each power storage cell 11, it is easy for condensed water to form on the top face 11 c and the bottom face 11 d, which are non-covered portions that are not covered by the condensation-preventing sheet, but since the top face 11 c of the power storage cell 11 is covered by the shielding portion 12 d of the intermediate power storage cell holder 12 or the end power storage cell holder 12B and the bus bar plate 28, a majority of the bottom face 11 d of the power storage cell 11 is covered by the first wall portions 19 a and 19 a of the pair of the lower insulators 19 and 19, and the openings a of the thermistor retaining portions 12 c of the intermediate power storage cell holders 12 into which the thermistors 21A and 21B are not fitted are only slightly open, by carrying out thermal insulation by covering the top face 11 e and the bottom face 11 d, on which condensed water easily forms, as much as possible, the formation of condensed water can be minimized and a liquid junction can be prevented from being formed (see FIG. 10 and FIG. 11).

Furthermore, if the peripheries of the power storage cells 11 are completed sealed, there is a possibility that a liquid junction will be formed between the power storage cells 11 themselves as a result of just a small amount of condensed water being formed, but due to part of the bottom wall 11 d being exposed by means of the opening α of the thermistor retaining portion 12 c, condensed water formed on the power storage cell 11 can be discharged to the outside via the opening α, thereby preventing a liquid junction from being formed between the power storage cells 11 due to condensed water.

Moreover, there is a possibility that a liquid junction will be formed if condensed water flowing out from the opening α makes the lower frame 16 beneath it in the vertical direction become wet, but since the first partition wall 19 d projects, in a canopy shape, from the first wall portion 19 a of the lower insulator 19 connected to the underneath of the opening α, it is possible to prevent the lower frame 16 from becoming wet due to the condensed water to thus form a liquid junction. Furthermore, since the pair of end power storage cell holders 12A and 12B include the second partition walls 12 j and 12 j, which surround the opening α in cooperation with the first partition walls 19 d and 19 d of the lower insulators 19 and 19, it is possible by means of the second partition walls 12 j and 12 j to reliably prevent condensed water that has flowed out from the opening α from forming liquid junction with the end plates 14 and 14 (see FIG. 10 and FIG. 11).

When condensed water formed on the top faces 11 c of the power storage cells 11 flows downwardly in the vertical direction and reaches the first wall portion 18 a of the upper insulator 18, since the large number of first ribs 18 f, which extends vertically, are formed on the surface of the first wall portion 18 a, condensed water is guided downwardly by the first ribs 18 f and prevented from flowing toward the end plates 14 and 14 side along the upper insulator 18, thereby preventing a liquid junction from being formed between the power storage cells 11 and the end plates 14 and 14 via the upper insulator 18 (see FIG. 6).

Condensed water guided downwardly by means of the first ribs 18 f is temporarily retained by the V-shaped second ribs 18 g, and condensed water temporarily builds up between the first ribs 18 f and the second ribs 18 g; after a fixed amount of condensed water has built up it drops downward, thus making it difficult to form uninterrupted condensed water, electrical contact between the power storage cells 11 and a component made of metal that is present in the vicinity thereof (for example, the support plate 29) via uninterrupted condensed water is prevented, and as a result the formation of a liquid junction can be prevented. Moreover, since condensed water formed on the power storage cells 11 flows downwardly along the upper insulator 18, it is also possible to prevent effectively a liquid junction from being formed between the power storage cells 11 clue to the condensed water.

Furthermore, the fifth wall portion 18 e of the upper insulator 18, the third wall portion 19 c of the lower insulator 19, and the pair of first wall portions 12 g and 12 g of the pair of end power storage cell holders 12A and 12B are disposed as a rectangular frame-shaped wall inside the space bounded by the upper frame 15, the lower frame 16, and the pair of end plates 14 and 14. Since the lower end of the wall extends further downwardly in the vertical direction than the lower ends of the upper frame 15, the lower frame 16, and the pair of end plates 14 and 14, it is possible to prevent effectively condensed water flowing downwardly from the power storage cells 11 from contacting the upper frame 15, the lower frame 16, and the pair of end plates 14 and 14 (see FIG. 6).

Moreover, since the lower edges of the fifth wall portion 18 e of the upper insulator 18, the third wall portion 19 c of the lower insulator 19, and the pair of first wall portions 12 g and 12 g of the pair of end power storage cell holders 12A and 12B bend in a zig-zag shape, it is possible to make the drainage of condensed water good, thereby preventing further effectively a liquid junction from being formed between the power storage cells 11 and the upper frame 15, lower frame 16, and end plates 14 and 14.

Furthermore, the power storage module M is supported on the opening 29 a of the support plate 29, and since the lower edges of the fifth wall portion 18 e of the upper insulator 18, the third wall portion 19 c of the lower insulator 19, and the pair of first wall portions 122 and 12 g of the pair of end power storage cell holders 12A and 12B extend through the opening 29 a of the support plate 29 downwardly in the vertical direction, it is possible to prevent condensed water from contacting the support plate 29, thereby preventing the formation of a liquid junction via the support plate 29 (see FIG. 8).

Furthermore, condensed water formed on the surface of the end plate 14 becomes attached to the first discharge path 31 along the first face P1, opposing the end plate 14, of the end power storage cell holder 12A, and condensed water formed on the surface of the power storage cells 11 becomes attached to the second discharge path 32 along the second face P2, opposing the power storage cells 11, of the end power storage cell holder 12A. The former condensed water is non-galvanic water, whereas the latter condensed water is galvanic water; if the two are mixed, the entirety becomes galvanic water, and a liquid junction easily forms, therefore making it necessary to block the mixing thereof.

The first drainage channel 31 formed on the first face P1 of the end power storage cell holder 12A extends downwardly in the vertical direction and then bends outwardly in the stacking direction, whereas the second drainage passage 32 formed on the second face P2 of the end power storage cell holder 12A extends downwardly in the vertical direction in a straight manner, and it is therefore possible to separately discharge the non-galvanic water of the first drainage channel 31 and the galvanic water of the second drainage passage 32 so that they do not contact each other, thereby preventing a liquid junction from being formed between the power storage cells 11 and the end plate 14 (see FIG. 9).

Furthermore, since the first and second guide ribs 12 h, 12 h. 12 i, 12 i projecting outwardly in the stacking direction are formed on the periphery of the first face P1, and the first drainage channel 31 is connected to the inside thereof, it is possible to reliably discharge non-galvanic water on the first face P1 to the first drainage channel 31, thereby preventing the non-galvanic water from leaking from the first face P1 side to the second face P2 side and contacting the galvanic water. In this arrangement, since the part of the first drainage channel 31 that bends outwardly in the stacking direction is inclined so that the downstream side is low, it is possible to smoothly discharge the non-galvanic water of the first drainage channel 31, thereby preventing it from contacting the galvanic water of the second drainage channel 32 (see FIG. 8 and FIG. 9).

Moreover, since the first and second guide ribs 12 h and 12 h, 12 i, 12 i of the end power storage cell holder 12A include the separating parts a surrounding the fastening portions 15 a, 15 a. 16 a, 16 a of the upper frames 15 and 15 and the lower frames 16 and 16 for connecting the pair of end plates 14 and 14 with each other, it is possible to smoothly discharge condensed water formed on the surfaces of the upper frames 15 and 15 and the lower frames 16 and 16 to the first drainage channel 31, through which non-galvanic water flows, thus preventing it from flowing into the second drainage channel 32, through which galvanic water flows, and preventing the formation of a liquid junction between the upper frames 15 and 15 and lower frames 16 and 16 and the end plates 14 and 14.

Furthermore, since the edge of the opening 29 a of the support plate 29 is positioned between the outlet 31 a of the first drainage channel 31 and the outlet 32 a of the second drainage channel 32, and the edge is at a height that is lower than the height of the outlet 31 a of the first drainage channel 31 and higher than the height of the outlet 32 a of the second drainage channel 32, it becomes difficult for galvanic water discharged from the outlet 32 a of the second drainage channel 32 to flow beyond the edge of the opening 29 a of the support plate 29 and contact non-galvanic water discharged from the outlet 31 a of the first drainage channel 31, thereby reliably preventing a liquid junction from being formed due to contact between the galvanic water and the non-galvanic water (see FIG. 9).

Moreover, since the seal member 30 is disposed between the edge of the opening 29 a of the support plate 29 and the end power storage cell holder 12A, it is possible to more reliably prevent contact between the non-galvanic water on the first drainage channel 31 side and the galvanic water on the second drainage channel 32 side. Furthermore, since the support plate 29 is tilted so that the first drainage channel 31 side is lower than the second drainage channel 32 side, it is possible to prevent condensed water that has dropped from the first drainage channel 31 on the support plate 29 from flowing back toward the second drainage channel 32 side, thus preventing the formation of a liquid junction.

The operation of the end power storage cell holder 12A on one side is explained above, but the operation of the end power storage cell holder 12B on the other side is the same.

An embodiment of the present invention is explained above, but the present invention may be modified in a variety of ways as long as the modifications do not depart from the spirit and scope thereof.

For example, the power storage cell 11 of the embodiment is not limited to a lithium ion battery and may be another type of battery or capacitor.

Furthermore, in the embodiment the first rib 18 f and the second rib 18 g are provided only on the upper insulator 18, but a first rib and a second rib may be provided on the lower insulator 19.

Moreover, in the embodiment the first rib 18 f is formed in a direction that is perpendicular to the stacking direction, but it is not necessary for the first rib 18 f to be perpendicular to the stacking direction, and if it is inclined relative to the stacking direction desired operational effects can be obtained.

Moreover, in the embodiment condensed water is explained, but needless to say the present invention is also effective with respect to electrolyte that has leaked from the power storage cell 11 or water that has entered from the outside. 

The invention claimed is:
 1. A power storage module comprising a plurality of power storage cells that are stacked in a stacking direction, a pair of end plates that are superimposed on outermost ones of the power storage cells at opposite ends in the stacking direction, a frame that is connected to the pair of end plates via fastening portions at opposite ends, and an insulating insulator that is clamped between the frame and the power storage cells, wherein in a mounted state the insulator comprises a first rib that extends in a direction intersecting the stacking direction, wherein the insulating insulator extends over an area covering the outermost ones of the power storage cells in the stacking direction and is opposed to all of the plurality of power storage cells, and wherein the first rib protrudes outwardly and integrally from a flat surface of the insulating insulator from a side opposite the power storage cells toward a direction away from the power storage cells.
 2. The power storage module according to claim 1, wherein the insulator comprises a plurality of the first ribs that extend vertically, and comprises a plurality of second ribs that connect adjacent first ribs in a V-shape.
 3. The power storage module according to claim 1, wherein the insulator comprises a downwardly extending portion that extends further downwardly than a lower end of the frame in a vertical direction.
 4. The power storage module according to claim 3, wherein a lower edge of the downwardly extending portion bends in a zig-zag shape.
 5. The power storage module according to claim 3, wherein the module comprises an insulating power storage cell holder held between one of the pair of end plates and one of the outermost power storage cells, the power storage cell holder comprises a downwardly extending portion that extends further downwardly than the lower end of the frame in the vertical direction, and the downwardly extending portion of the insulator and the downwardly extending portion of the power storage cell holder surround a periphery of the plurality of power storage cells in cooperation.
 6. The power storage module according to claim 1, wherein the insulator is subjected to a water-repellent treatment.
 7. The power storage module according to claim 6, wherein a section, where the rib is present, of the insulator is subjected to a water-repellent treatment.
 8. A fixing structure of a power storage module, the structure fixing the power storage module according to claim 1 onto a support plate, wherein the support plate and the frame oppose each other, and a vertically lower end of the insulator is at a position lower than the support plate in the vertical direction. 